1. Field of the Invention
The invention relates to a compact system with high homogeneity of the radiation field, compared with arrangements that are known in the state of the art.
2. Description of the Related Art
It is known to use radiation, in particular UV- or IR-radiation for the treatment of water, gasses, in particular air, or surfaces. Particularly known is disinfection with UV-radiation. Relatively wide spread is drinking water treatment with UV-radiation, whereby the bacterial count in the water, subject to the dosage can be reliably and significantly reduced. Microorganisms, such as pathogens, in particular bacteria or viruses, are inactivated through UV-radiation.
The level of efficiency of a treatment system is determined to a large extent by the homogeneity of the created radiation field in which the medium that is to be treated, for example water, is located. In particular in systems with few light sources, achievement of sufficient homogeneity is difficult and usually associated with high efficiency losses. For treatment efficiency it is therefore preferred to provide an as homogeneous distribution of the radiation intensity as possible. A local increase of the radiation intensity is thereby not harmful. However, a locally strongly reduced intensity may result in insufficient treatment. In the case of disinfection by means of UV-radiation, for example germs that flow through these regions during passage through a UV-reactor are not sufficiently deactivated.
Moreover, a compact design of the treatment system is important for applications in areas where there is a significant lack of space, without however entering into compromises in regard to system efficiency. In addition, due to spatial issues and often also due to aspects of cost the number of radiation sources must be reduced as far as possible.
Two conceptual approaches for UV-disinfection are known from the current state of the art:
In the first concept, high compactness of the arrangement is achieved, whereby however at the same time the radiation homogeneity suffers. A typical example of such an arrangement is the coaxial geometry. FIG. 1a illustrates an exemplary embodiment of such a system, as is known from the current state of the art. FIG. 1a shows a top view of a tubular shaped UV-light source 1 that extends perpendicular to the drawing plane, is arranged inside a tube 7 and is surrounded by a medium such as water. UV-light source 1 is thereby protected from the water by a UV-transparent encasement tube 5. Due to the quadratic decrease of the radiation intensity of the UV-light source with the distance, and the additional weakening due to absorption in the medium, an inhomogeneous radiation field results in FIG. 1a. 
To clarify the inhomogeneous radiation field from FIG. 1a, the type of the radiation field which results for an arrangement according to FIG. 1a is illustrated in detail in FIG. 1b on the basis of the so-called ray tracing method. In the ray tracing method ray paths originating from the radiation source are calculated, whereby the optical parameter of the penetrated materials, in particular absorption and reflection coefficients are considered. By calculating a high number of statistically produced output rays, the resulting radiation field is mapped. This method is known to the expert from the current state of the art and therefore requires no further explanation.
In FIG. 1b it is shown how the radiation field in the arrangement of FIG. 1a portrays itself, whereby the individual UV light source 1 is arranged in the center, inside tube 7. The two diagrams on the bottom and the right edge in FIG. 1b are sectionals respectively showing the progression of the radiation density. The bottom diagram shows the radiation intensity in a horizontal section through the center of the drawing (z millimeter) and the right diagram shows the radiation intensity in a vertical section through the center of the drawing (y millimeter). Regions through which no medium is conducted are masked out in the drawing. The diagrams therefore illustrate the radiation intensity along the selected sectional planes. A perfectly homogeneous radiation field would result in a flat horizontal line (so-called “hat profile”). A strongly inhomogeneous radiation field results in a strong deviation of the values along the selected section. It can therefore be seen in FIG. 1b that the radiation intensity is at a maximum near the UV-light source and drops off markedly toward the outer edge of the tube. For the arrangement in FIG. 1a a standard deviation of 43% from the mean value of the radiation intensity was calculated according to FIG. 1b. Such a high value proves poor radiation homogeneity of the system. The arrangement according to FIG. 1a therefore is very compact, has however a very inhomogeneous radiation field. A strongly inhomogeneous radiation field means in this case however, that there are regions in which existing germs which flow through these regions during passage through tube 7 are not sufficiently radiated to be rendered inactive, due to the low radiation intensity. The disinfection efficiency is therefore insufficient.
The following are additional exemplary devices for disinfection from the current state of the art which are also designed relatively compact but command insufficient radiation homogeneity:
US 2007/0272877 A1 relates to a radiation device, in particular a UV disinfection device, including at least one reactor for treatment of fluids by way of light radiation, whereby the reactor includes a tube or respectively a channel or a container consisting of a transparent material and surrounded by air. The radiation device includes a fluid inlet, a fluid outlet, and at least one opening or a window which is adapted for the transmission of light into the tube or respectively the channel. Outside the tube or channel a light source is located, having a light generator and a reflector in order to reflect the light that is produced by the light generator in the direction of the window in a predefined angle region. In particular, a cylindrical reactor is provided for this, which can be designed at least partially so that light, in particular UV light impinging on the walls is reflected back into the medium.
U.S. Pat. No. 6,337,483 B1 relates to a germicidal UV chamber for use with air, whereby the UV chamber itself can be in the embodiment of a reflector and preferably has the shape of a ellipsoid cut off at both ends.
The disclosure in U.S. Pat. No. 6,555,011 B1 relates to a method for disinfection and cleaning of liquids and gasses wherein a special reactor design is applied, wherein the reflective side walls contribute to the concentration of the UV radiation during disinfection of liquids and gasses
US 2010/0264329 A1 moreover relates to a disinfection device for liquids with the assistance of light, whereby the device includes: a substantially light-transparent tube to disinfect liquid flowing through it; a substantially light-transparent encasement having outside dimensions which are smaller than the inside dimensions of the tube, whereby the encasement in the tube is arranged substantially perpendicular to the axis of symmetry of the tube; as well as a light source which is arranged inside the encasement. A quartz glass tube preferably serves as the reactor and is located inside reflective walls of a reflector.
U.S. Pat. No. 5,216,251 A describes a disinfection and drying device for hands and forearms, whereby UV light is used in a working chamber in order to disinfect pre-heated air from a second chamber that is connected with the working chamber, to then thereby disinfect and dry the hands or arms in a closed chamber. The disinfected medium is utilized in the form of air to disinfect and dry the hands, whereby disinfection therefore occurs in a more or less enclosed space.
In the second conceptual approach according to the current state of the art UV disinfection systems are provided, that indeed produce a relatively homogeneous radiation field, but require an extraordinarily large space for this and are therefore not designed sufficiently compact:
GB 2 334 873 A for example, describes a sterilization device including a multitude of elliptical reflectors. In FIG. 1 of GB 2 334 873 A an elliptical double reflector 1 is arranged around a test tube 2, whereby the test tube is arranged at the common focal point of the reflector. Two mercury lamps 3 are positioned at the other two focal points of the elliptical double reflector 1.
U.S. Pat. No. 5,247,178 A moreover discloses a device for treatment of a fluid by means of radiation of a thin film of the fluid with concentrated light of high intensity. An annular fluid passageway 102 is provided for radiation so that a thin film of the fluid to be radiated is available. On the interior the annular passageway 102 is defined by a shaft 103 whose surface is reflective. Externally the annular passageway 102 is surrounded by a transparent tube 104. An elliptical reflective cylinder 101 is provided, whereby the radiation source is arranged at or near the first focal point of the elliptical cylinder and the medium that is to be radiated is arranged at or near the second focal point, as seen in detail in FIG. 1 of U.S. Pat. No. 5,247,178 A.
According to the teachings of GB 2 334 873 A, as well as of U.S. Pat. No. 5,247,178 A the UV light sources are therefore arranged outside the UV reactor. Through the arrangement of externally positioned reflectors the UV radiation is coupled as uniformly as possible through the UV-transparent reactor wall into the medium. Currently known systems use reflectors for this purpose whose reflective surfaces are generally separated from the UV-transparent reactor wall. The UV-light is distributed outside the medium-conducting UV reactor such that an as homogeneous as possible radiation field inside the UV-reactor results.
From the current state of the art according to DE 38 24 647 A1 a device for radiating media by means of UV light is also known, consisting of a tubular body through which media flows and which consists of an UV-permeable material, and at least two UV light sources with reflectors, arranged axially parallel on the outside, whereby the light sources are flat UV emitters having an elongated, flat-oval cross section with wide and narrow side, whereby the primary axis of the UV light sources are always directed upon the center point of the tubular body's cross section. The UV light sources are arranged annularly and axially parallel around the tubular body through which media flows. According to one design variation the flat emitters fit closely against the tubular body with the narrow side that is facing toward the tubular body. In this configuration, the UV reactor is not in the embodiment of a reflector. The reflectors are exclusively assigned to the UV light sources and do not form any part of the UV reactor itself through which the medium that is to be disinfected flows. The arrangement according to DE 38 24 647 A1 moreover requires a large space due to the UV light sources being positioned on the outside.
Arrangements of this type facilitate a relatively homogeneous radiation field inside the medium that is to be disinfected. However, the large space that is required for radiation distribution is detrimental with these arrangements. Systems according to the second conceptual approach are therefore not suitable for applications with space restrictions.
Systems known from the current state of the art are therefore either compact, but offer insufficient radiation homogeneity; or systems known from the current state of the art achieve indeed high radiation homogeneity, but require a large space for this which rules out applications in confined installation locations.
What is needed in the art is a system wherein the disadvantages of the current state of the art are avoided, in other words a system which provides sufficiently high radiation homogeneity and at the same time has a very compact design.